Ant Traits, Myrmecophiles, and Disturbance
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Ant traits, myrmecophiles, and disturbance James Glasier Evolution and Ecology Research Centre School of Biological, Earth and Environmental Sciences University of New South Wales August 2017 A thesis in fulfilment of the requirements for the degree of Doctor of Philosophy PLEASE TYPE THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: Glasier First name: James Other name/s Abbreviation for degree as given in the University calendar: PhD School: School of Biological, Earth and Environmental Sciences Faculty: Science Title: Ant traits, myrmecophiles, and disturbance Abstract 350 words maximum (PLEASE TYPE) Ants are eusocial insects that are diverse, abundant, and globally widespread. These attributes allow ants to play an important role in terrestrial ecosystems; such as significantly contributing to soil turnover, predator-prey relationships, and facilitating biodiversity. This thesis examines how environmental factors and species traits, play a role in determining symbiotic relationships, as well as determining resilience to disturbance. Chapter 1 looks at why ants are good focal taxa to study a wide range of ecological questions including symbiotic associations, climatic influence in species richness, and habitat disturbance on communities. Chapters 2, 3, and 4 involved a database of ants and myrmecophiles, synthesized by me from 351 references, that included 622 ants and 1629 myrmecophiles. In Chapter 2, I examined if the global species richness of myrmecophiles and their symbiotic relationships, was determined by regional ant species richness or climatic variables associated with a latitudinal gradient. I found that both ant species richness and climatic variables influenced myrmecophile richness, but richness of symbiotic relationships were more affected by climatic variables. In Chapter 3, I looked at ant traits such as colony size, diet or morphological traits and determined which were correlated with more myrmecophile associations. I found that large colony size (>1000 000) and number of spines, played an important role in explaining the number of myrmecophiles associated with an ant. Chapter 4 models the host range of different myrmecophile relationships at the species level, contrasting relationship type and taxonomic group to determine if myrmecophiles with beneficial or detrimental relationships have more hosts. I found that beneficial relationships had a higher number of associations compared to detrimental ones. For Chapter 5, I did a field study looking at the effects of grazing intensity and history on below- and aboveground ant communities within the arid woodlands of New South Wales. I found that below-ground communities were resilient to grazing disturbance, and that grazing history had a great er affect on above-ground communities than grazing intensity. Chapter 6 summarizes my findings, discusses the implications of my work, the limi tations of the studies, and suggests future paths of research on ants and myrmecophiles. Declaration relating to disposition of project thesis/dissertation I hereby grant to the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University libraries in all forms of media, now o r here after known, subject to the provisions of the Copyright Act 1968. I retain all property rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstracts International (this is applicable to doctoral theses only). Signature Witness Date The University recognises that there may be exceptional circumstances requiring restrictions on copying or conditions on use. Requests for restriction for a period of up to 2 years must be made in writing. Requests for a longer period of restriction may be considered in exceptional circumstances and require the approval of the Dean of Graduate Research. FOR OFFICE USE ONLY Date of completion of requirements for Award ORIGINALITY STATEMENT ‘I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged.’ Date ………………………….............. COPYRIGHT STATEMENT ‘I hereby grant the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstract International (this is applicable to doctoral theses only). I have either used no substantial portions of copyright material in my thesis or I have obtained permission to use copyright material; where permission has not been granted I have applied/will apply for a partial restriction of the digital copy of my thesis or dissertation.' Date ……………….………........................... AUTHENTICITY STATEMENT ‘I certify that the Library deposit digital copy is a direct equivalent of the final officially approved version of my thesis. No emendation of content has occurred and if there are any minor variations in formatting, they are the result of the conversion to digital format.’ Date ……………….…………........................... ii Abstract Ants (Family Formicidae) are eusocial insects that are diverse, abundant, and globally widespread. These attributes allow ants to play an important role in terrestrial ecosystems; such as significantly contributing to soil turnover, nutrient cycling, predator-prey relationships, and facilitating biodiversity, through close associations with other organisms. This thesis examines how environmental factors and species traits, play a role in determining these species associations, as well as determining resilience to disturbance. Chapter One looks at why ants are a good focal taxon to study a wide range of ecological questions including symbiotic associations, climatic influence in species richness, and habitat disturbance on communities. Chapters Two, Three, and Four involved a database of ants and their myrmecophiles (organisms associated with ants), synthesized by me from 351 references, that included 622 ant and 1629 myrmecophile species. In Chapter Two, I examined if the global species richness of myrmecophiles (organisms that capitalize on the social fabric of ant biology) and their symbiotic relationships (mutualisms, commensalisms, kleptoparasitisms, and parasitisms), was determined by regional ant species richness or climatic variables associated by the common latitudinal gradient (for example: average annual temperature, precipitation, and net primary productivity). I found that both ant species richness and climatic variables were important for overall myrmecophile species richness, but for the symbiotic relationships, climate had greater effect on species richness overall. In Chapter Three, I look at species specific ant traits such as colony size, diet or morphological traits such as number of spines or functional stingers, and determined which traits were correlated with more myrmecophile associations. I found that large colony size (>1000 000), number of iii spines and diet, played an important role in explaining the number of myrmecophiles associated with an ant. Chapter Four models the host range of different myrmecophile relationships at the species level, contrasting relationship type and taxonomic group to determine if myrmecophiles with beneficial or detrimental relationships interact with more hosts. I found that beneficial relationships, and taxa that were involved in these relationships had a higher number of associations compared to detrimental ones. For Chapter Five, I did a field study looking at the effects of grazing intensity and history on below- and aboveground ant communities within the arid woodlands of New South Wales. I found that below-ground communities were resilient to grazing disturbance, and that grazing history had a greater affect on above-ground communities than grazing intensity. My last chapter, Chapter 6 summarizes my findings, discusses the implications of my work, the limitations of the studies, and suggests future paths of research on ants and myrmecophiles. iv Acknowledgments First, I would like thank my supervisor David Eldridge for all his advice and guidance throughout the course of this research. Thank you for giving me the opportunity to do this work and assist me in studying ants! I am also thankful to Alistair Poore for his advice in research structure and statistical design. Thank you to the Examiners